China Hot DIP Galvanizing Production Line factory
Three key links of continuous hot dip galvanizing production line should be strictly controlled:
1. Preplating treatment:
Before plating processing, is the foundation of the plating, also is the key to guarantee product quality, not before plating will be to the requirements of the plating substrate processing, even if there is a good plating solution, the proper plating parameters and good regulation electroplating equipment and skilled personnel, it is impossible to meet the requirements of the quality of plating, electroplating before not only to remove grease and influence of matrix on the metal coating adhesion and other quality requirements of foreign body, also want to remove the surface oxide, make its have the specified cleanliness and surface activity, to ensure that the coating and the substrate firmly with, sometimes according to the requirements of the appearance of the plating, and some other special pretreatment before plating. Standard :GB/ t12611-90)
2. Plating process control
Electric galvanized metal or use condition and the service life of components and has close relation with the plating thickness, using more rigorous conditions and the service life is longer, the required electric galvanized layer should be more thick, different products, according to the use of specific environment (temperature, humidity, rainfall, atmospheric composition, etc.) to determine the expected service life of plating thickness, blind thickening can cause all kinds of waste, but if the thickness is not enough, and will not reach the expected service life requirements,
Different manufacturers, according to their own equipment conditions, in the determination of plating species, first of all to prepare a set of relatively complete and reasonable process flow, clear plating parameters, control the concentration of electroplating solution, conduct standard operation.
3. Post-plating treatment:
Post-plating (passivation, hot melting, sealing and dehydrogenation, etc.) for the purpose of enhancing protective properties, decorative properties and other special purposes.
After galvanizing, chromate passivation or other transformation treatment should be generally carried out to form the corresponding type of conversion film, which is one of the key processes to ensure the quality after plating. After passivation, aging treatment should also be carried out (70-80 "C in oven). Passivation can be divided into the following forms:
(1) color obtuse: HNO3, H2SO4, Cr03 (indispensable triacid)
(2) blue and white blunt: F+Cr
(3) silver white blunt: BatCr
(4) black blunt: Cr+Ag or Cr+Cu
(5) golden yellow blunt: Cr+ reducing agent
Color blunt: suitable for zincate galvanized, surface passivated parts for red, green, slightly yellow (Crf6 red, Cr + 3 "green), cannot appear purple (after passivation film loose), the simplest method is to use the fingers on the parts surface reciprocating friction a few times, can not change color (off). Blue white blunt: as the fluoride in the passivation solution gradually decreases with longer time, therefore, blue parts surface will becomes shallow gradually, the same class production of artifacts to keep color is bad, so want to rein in the process of passivation, and pay attention to the thickness
Silver white blunt: does not change with time, color and color maintain good consistency.